I propose a two-phase plan for training in preparation for an academic research career in gastrointestinal oncology. In the first phase, I will take courses in molecular biology, molecular genetics, virology and cancer biology/genetics in the Graduate School of Biomedical Sciences. l will develop laboratory skills in cell and molecular biology and initiate a research plan which will become the major focus of phase II. Twenty percent effort will be spent in clinical gastroenterology and oncology to maintain my clinical skills. In vivo, cancer cells escape normal growth regulation and behave autonomously. Malignant cells in culture behave similarly and are immortal. Few, if any, normal human cells show immortality. Therefore immortalization appears to be an important step in human carcinogenesis. The transformation to immortality will be studied by using a unique series of matched preimmortal and immortal SV40 transformed human fibroblast (SV1HF) cell lines. A cDNA library has been prepared from a preimmortal SV/HF (SVtsA/HF-C) and analyzed by subtraction hybridization. A series of cDNAs have been identified which detect mRNAs which are differentially expressed in immortal cell lines. Representative cDNAs will be further characterized to assess their role in immortalization. mRNA underexpressed in immortal cells will be tested for growth suppressor function. mRNA overexpressed in the immortal cell line will be tested for growth stimulation. The full length cDNA will- be isolated from the appropriate expression library. Its effect on growth in normal proliferating and senescent cells, preimmortal and immortal cells will be determined using transient and stable expression assays. Several immortal cell lines will be studied to verify consistency. Determining the secondary effectors of immortality may lead to novel approaches in cancer prevention, detection and treatment. These approaches will later be applied to the specific study of gastrointestinal malignancy.